<script src="lib/js/zepto.js"></script>

<script>



    Zepto(function ($) {
        var startY = 0; 
        var nav_top = -50;//目标的高度负值
        var $floating;  //目标
        var $body;      //触控屏幕的相应位置
        var startOffsetTop;  //点击屏幕时目标相对父元素的Y位置 
        var startScrollY;   //点击屏幕时scroll的位置，用于Andriod的touchMove bug
        var startTime;
        var bIsAndr = isAnDriod();
        $floating = $(".floating-top");
        $body = $("body");
        
        //touchstart
        $body.on("touchstart", function (e) {
            var oTouch = e.touches[0];
            startY = oTouch.screenY;
            startOffsetTop = $floating.offset().top;
            //for Andriod兼容,假如不除这个bug，当先下滚不松手再上滚时，导航条不显示
            //可用不直接置顶nav的方法，上滚时才添加fixed样式执行动画，(添加动画结束等待?),下滚时判断是否有fixed的样式，有则去除
            //if (false && bIsAndr) {
            //    e.preventDefault();
            //    startScrollY = window.scrollY;
            //    //用于touchend后的继续滚动计算
            //    //var startTime = new Date().getTime();
            //}
                
        });

        //touchmove
        $body.on("touchmove", function (e) {
            var oTouch = e.touches[0];
            var nowY = oTouch.screenY;
            var dist = nowY - startY;
            fAminTheNav(startOffsetTop, nav_top, dist);
            //for Andriod兼容
            //if (false && bIsAndr) {
            //    fScrolling(startScrollY, dist);
            //}
            
        });
        //滚动屏幕
        function fScrolling(startScrollY, dist) {
            window.scroll(0, startScrollY - dist);
        }
        //显示或隐藏目标
        function fAminTheNav(startOffsetTop, nav_top, dist) {
            var actValue;
            if ((dist >= 0) || ((startOffsetTop < -nav_top) && dist > nav_top)) {
                actValue = 'translate3d(0,' + 0 + 'px,0)';
            } else {
                actValue = 'translate3d(0,' + nav_top + 'px,0)';
            }
            //$("#log").html(nowY);
            $floating.css({
                '-webkit-transform': actValue,
                '-moz-transform': actValue
            });
        }
        //是否andriod
        function isAnDriod() {
            if (navigator.userAgent.match(/Android/i)) {
                return true;
            } else {
                return false;
            }
        }
    });
    Zepto(function ($) {
        $(document).on("click", ".check-box", function () {
            $(this).toggleClass("checked");
        })
    })

</script>
